False generic error: Method never returns null so ..

[Jeroeny]

Bug report

Given the method

    /** @return T|null */
    final public function randValue(): mixed

In a generic Collection. Then using that method somewhere:

	private function rand(): ?User
	{
		return $this->collection->randValue();
	}

yields the error: Method User::rand() never returns null so it can be removed from the return type..

Code snippet that reproduces the problem

https://phpstan.org/r/a70699a3-6415-4bc6-8247-7b55a57040dc

Expected output

No errors.

Did PHPStan help you today? Did it make you happy in any way?

PHPStan still helps a lot :)

[Jeroeny]

Apparently PHPStan thinks mixed return type never returns null: https://phpstan.org/r/a4940517-dc71-4766-89c8-0bb774b95b63

But it can: https://3v4l.org/ANhir

[phpstan-bot]

@Jeroeny After the latest commit in dev-master, PHPStan now reports different result with your code snippet:

@@ @@
-73: Method User::rand() never returns null so it can be removed from the return type.
+No errors

[github-actions]

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